1. Technical Field
This invention relates generally to rechargeable batteries for portable electronic devices, and more specifically to auxiliary rechargeable batteries with means of attachment to garments and other objects.
2. Background Art
Portable electrical devices rely upon rechargeable batteries for their portability. Products ranging from power tools to cellular phones each depend upon a battery to be able to operate without a cord attached to an outlet. These rechargeable batteries are manufactured using many different chemistries, including nickel-based chemistries, like nickel metal hydride (NiMH) and nickel cadmium (NiCad), and lithium-based chemistries, like lithium ion and lithium polymer. Each of these chemistries offers certain advantages. For example, lithium batteries are generally lightweight, with high energy densities. Nickel batteries, while being quite heavy, generally offer higher peak current capability.
For low current applications, like cellular phones, lithium batteries work quite well. Since they are very lightweight, they may be coupled directly to the electronic device without causing strain or inconvenience to the user. Power tool applications, like drills and saws for example, typically require higher peak currents than that provided by lithium cells. For this reason, nickel based cells are generally used for power tool applications.
While nickel cells work well in power tool applications, the additional weight added by coupling as many as twelve cells to a tool can cause problems. For example, imagine a carpenter working on the ceiling of a new home. If the carpenter is forced to hold a drill, with three pounds of batteries attached, above his head for eight or more hours, he may grow tired. His tired and sore muscles may compromise the accuracy of his drilling.
Prior art solutions have attempted to solve this problem by removing the weight of the batteries from the power tool. By way of example, U.S. Pat. No. 6,106,971, entitled “Portable Power Tool Having Low Rate, Rechargeable Batteries Attached to Clothing,” issued to Spotnitz on Aug. 22, 2000, teaches one such solution. Referring now to FIG. 1, illustrated therein is a means for attaching batteries 16 to clothing 34 in a traditional manner (i.e. by way of sewing) as taught by Spotnitz. The batteries 16 couple to the power tool 12 by way of a cable 22 that may be optionally coupled to a reel 20. Pockets 32 appear on the clothing 34 into which batteries are disposed. By wearing the battery clothing 34, the user 30 does not need to sustain the weight of the batteries 16 above his head.
The problem with this prior art solution is that it requires special clothing. The batteries must either be sewn into the garment, or the garment must provide special pockets with electrical connections to couple the batteries in parallel as taught by Spotnitz. In either case, the user must purchase an expensive, special piece of clothing. He must wear the clothing each time he uses the power tool. To make matters worse, clothing with electrical connections invariably must be professionally cleaned. A workman who uses such a garment regularly may not be prone to dry cleaning the garment on a daily basis. After repeated uses without cleaning, the odor emitted by the garment may be distracting to other workers on the site, again compromising work output.
There is thus a need for an improved, detachable battery pack.